Compactors are widely used in the construction and landscaping industries for the compaction of granular materials. Compactors can have a variety of different configurations including vibratory rammers, vibratory plate compactors and vibratory roller (or drum) compactors. Applications for compactors may include the compaction of sand, gravel, or crushed aggregate for foundations, footings, or driveways; base preparation for concrete slabs, asphalt parking lots, etc. Compactors can also used for the compaction of either hot or cold mix asphalt during patching or repairing of streets, highways, sidewalks, parking lots, etc.
A typical vibratory compactor includes at least one roller that functions to compact a surface. The roller includes a vibratory mechanism that may include an eccentric shaft which can be accelerated by a motor, such as a hydraulic motor, in order to impart vibrations to the roller. Generally, the eccentric shaft has one or more weights press-mounted or welded on the eccentric shaft to achieve a desired eccentric mass. A second motor may be provided to rotate the roller, and thereby move the vibratory compactor forward/backward over the surface to be compacted.
The eccentric shaft may be relatively heavy in weight in order to provide the desired vibrating force on the roller. As a result, the hydraulic motor associated with the eccentric shaft must be capable of producing a relatively high start-up torque to accelerate the eccentric shaft, such as at the beginning of a compacting job. The need to produce this start-up torque can lead to the need for a relatively larger engine for the compactor to power the eccentric shaft motor, which can increase the cost of the compactor as well as increase the amount of emissions produced by the compactor. The large start-up torque can also lead to higher operating costs and wear and tear on the eccentric shaft motor.